Interconnect scheme for mounting differently configured printheads on the same carriage

ABSTRACT

A printer/plotter having a carriage for removably mounting a plurality of printheads, with one type of printhead such as a wider swath higher resolution black inkier cartridge having one type of electrical interconnect and another type of printhead such as a narrower swath lower resolution color inkjet cartridge having a different type of electrical interconnect. The carriage includes differently configured flex-circuit conductive assemblies for each different type of electrical interconnect without having to change the datum configuration of the cartridges mounted in the carriage.

RELATED APPLICATIONS

This application is related to copending application filed on Oct. 29,1993 as Ser. No. 08/145,261 in the name of Messrs. Donald G. Harris,Majid Azmoon and Gary M. Nobel entitled MIXED RESOLUTION PRINTING FORCOLOR AND MONOCHROME PRINTERS, which application is assigned to theassignee of this application and is incorporated herein by reference.

This application also relates to the following copending applicationswhich are commonly owned by the assignee of this application, and whichare incorporated herein by reference:

ELECTRICAL INTERCONNECT SYSTEM FOR A PRINTER filed as Ser. No. 08/56,345on Apr. 30, 1993 in the names of Arthur K. Wilson, et al.; MODULARCARRIAGE ASSEMBLY FOR AN INKJET PRINTER filed as Ser. No. 08/55,618 onApr. 30, 1993 in the names of Arthur K. Wilson, et al.; WIPING STRUCTUREFOR CLEANING ELECTRICAL CONTACTS FOR A PRINTER AND INK CARTRIDGE filedas Ser. No. 08/56,009 on Apr. 30, 1993 in the names of Corrina A. E.Hall, et al.; METHOD AND DEVICE FOR PREVENTING UNINTENDED USE OF PRINTCARTRIDGES filed as Ser. No. 08/56,961 on May 3, 1993 in the names ofJeffrey A. Thoman, et al.; SIDE BIASED DATUM SCHEME FOR INKJET CARTRIDGEAND CARRIAGE filed as Ser. No. 08/57,241 on Apr. 30, 1993 in the namesof David W. Swanson, et al.; and PRINTHEAD WITH REDUCED INTERCONNECTIONSTO A PRINTER filed as Ser. No. 07/958,833 on Oct. 8, 1992 in the namesof Michael B. Saunders, et al.

BACKGROUND OF THE INVENTION

This invention relates generally to printers/plotters, and morespecifically to print carriages having inkjet print cartridges removablymounted thereon.

It is common to have several inkjet print cartridges in a singlecarriage of an inkjet printer. But in some instances these cartridgesmay have different capabilities and therefore have different electricalinterconnect designs connecting the cartridges to the printer. Forexample, the number and pattern of electrical contacts may differbetween the different types of cartridges, such as in cartridges whichhave different print resolutions.

Many multi-pen set printers have addressed the issue of improving outputquality and the speed of output without increasing the resolution of theentire pen set and thus their cost and complexity. Some have improvedoutput quality through improved addressability and some through improvedprinting algorithms. In such cases the improved output quality is not asgood as the output quality from the higher resolution pen of themulti-resolution pen set.

Typically in inkjet printers, one print cartridge is black, another is atri-compartment color cartridge, or a separate color cartridge isprovided for each color component (e.g., cyan, magenta, yellow). Thedifferent types of nozzle arrays and differently designed color andblack print cartridges, as well as other unique printheadcharacteristics all create the need for an inexpensive but reliable wayto successfully mount such different cartridges into the same carriage.

BRIEF SUMMARY OF THE INVENTION

A principal object of the invention is to incorporate printheads havingdifferent types of electrical interconnects into the same carriage inorder to expand the capabilities of the printer to achieve high qualityprinting as well as greater throughput. A related object is to decreaseresearch and development costs as well as decrease the time for bringinghigher resolution printers to market.

It is a primary object of the invention to adapt a print carriage forremovably mounting differently configured print cartridges at the sametime in the same carriage without having to change the datumconfiguration for the print cartridges.

Another object is to provide a modified interconnect scheme for acarriage mounted flex-circuit member having an increased number ofconductive pads spread over an enlarged area without having to changethe size of the carriage chute for receiving a print cartridge. Arelated object is to provide a simplified unitary resilient member madeof foam or the like which assures pressurized interconnection of all ofthe increased number of conductive pads over their enlarged area.

A further object is to provide an interconnect scheme which allowsremovably mounted print cartridges with different nozzle array densitiesactivated by differently configured conductive pad arrays to besimultaneously seated in a carriage having substantially identicalmounting chutes.

In its preferred form, the invention provides a modular carriage havinga customized flex-circuit frame for interconnecting three separate colorprintheads each having thirty-two conductive interconnect pads in afour-column array in conjunction with a first corresponding resilientscheme, as well as for interconnecting at the same time a singleseparate black printhead having fifty-two conductive interconnect padsin a six-column array in conjunction with a newly developed resilientscheme. The color printheads each have approximately one-hundred nozzlesarrayed in a swath of approximately 1/3 inch to achieve a 300 dpiresolution, and the black printhead has three-hundred nozzles arrayed ina 1/2 inch swath in order to achieve a 600 dpi print resolution.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a typical inkjet printer which can incorporate theapparatus and method of the present invention;

FIG. 2 shows a carriage having removable multi-color print cartridges,which can incorporated the apparatus and method of the presentinvention;

FIG. 3 shows an exemplary lower resolution color inkjet print cartridgeused in a presently preferred embodiment of the invention;

FIG. 4 is a perspective view of a carriage incorporating presentlypreferred embodiment of the invention in an inkjet printer;

FIG. 5 is a top view of the carriage of FIG. 4;

FIG. 6 is a fragmentary view of the flex-circuit interconnect on thecarriage of FIGS. 4 and 5, with the interior carriage walls cut away;

FIG. 7 is a schematic block diagram of the presently preferredembodiment of the invention;

FIG. 8 is a schematic bottom view as seen looking up from the mediashowing the alignment relationship of the nozzle arrays of FIG. 7;

FIG. 9 is a schematic view showing the use of a foam member foroperatively connecting a flex-circuit to a higher resolution blackinkjet cartridge;

FIG. 10 is an exploded view showing a flex-circuit frame portion of acarriage, with the foam member of FIG. 9 for assuring pressureconnection of a flex-circuit to a higher resolution black inkjetcartridge, and a metal spring member for assuring pressure connection ofa flex-circuit to lower resolution color inkjet cartridges;

FIG. 11 is a front view of the flex-circuit frame of FIG. 10; and

FIG. 12 is a schematic diagram showing the relative resolution between a600 dpi printout of the black printheads and a 300 dpi printout of thecolor printheads of a presently preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In a multiple pen printer, it is important to improve the output qualityof a printed page and increase the speed at which that output can beobtained as economically and simply as possible. In a printer mechanism,the output quality of a printed page is a function of printheadresolution. The higher the resolution the better the print quality.Also, in a swath printer employing a scanning carriage, the speed atwhich the output can be obtained is a function of the width of the swathwhich is covered by the printhead.

In current multi-pen printers, each pen has the same resolution andusually the same swath width. This means that all the supportingstructure, mechanics and electronics needs to be scaled up to supportthe resolution of the entire set of pens. All this hardware is moreexpensive than the hardware to support a multi-resolution, multi-swathwidth pen set where one pen is at the higher resolution and larger widththat is desired and the other pens in the set are at a lower resolutionand smaller size.

This invention provides the benefits of a higher resolution, largerswath pen in lower resolution, smaller swath pens in the same printingmachine. The higher performance pen can be used to improve outputquality by enhancing certain key features that appear frequently in aprinted page such as text. Such a pen also improves thoughput by beingable to print these frequent features faster. The other lowerperformance pens can be used for less frequent or less demandingfeatures such as graphics.

In the presently preferred embodiment of the invention disclosed herein,we have combined a 600 dpi 1/2 inch swath black pen with three 300 dpicolor pens each generating a swath of approximately 1/3 inch. The highperformance black pen is typically used for printing text and other"black only" features, and thus the output quality and throughput ofthese features is greater. It also improves the output quality of colorgraphics and color features by teaming with the three lower performancecolor pens when printing color graphics or color features. The blackcomponent of the graphics which is often a large portion of colorgraphics content is at a higher resolution and thus at a higher outputquality level. The larger swath can then be combined with printingalgorithms to improve the throughput of color graphics.

Even though the invention can be used in any printing environment wheretext and/or graphics are applied to media using monochrome and/or colorcomponents, the presently preferred embodiment of the invention is usedin an inkjet printer of the type shown in FIG. 1. In particular, inkjetprinter 10 includes an input tray 12 containing sheets of media 14 whichpass through a print zone, and are fed past an exit 18 into an outputtray 16. Referring to FIGS. 1-2, a movable carriage 20 holds printcartridges 22, 24, 26, and 28 which respectively hold yellow (Y),magenta (M), cyan (C) and black (K) inks. The front of the carriage hasa support bumper 30 which rides along a guide 32 while the back of thecarriage has multiple bushings such as 34 which ride along slide rod 36.The position of the carriage as it traverses back and forth across themedia is determined from an encoder strip 38 in order to be sure thatthe various ink nozzles on each print cartridge are selectively fired atthe appropriate time during a carriage scan.

Referring to FIGS. 3-6, a 300 dpi color inkjet cartridge 40 having atab-circuit with a four column thirty-two pad electrical interconnect 42is removably installed in three chutes 44, 46, 48 of a unitary carriage50. A flex-circuit member 52 having three matching sets of conductivepads 54, 56, 58 is mounted on flex-frame pins 60 for operativeengagement with the cartridge pads when the cartridge is inserted intoits appropriate chute. An enlarged set of conductive pads 62 covering alarger area, having a different layout, and constituting an array of sixcolumns totaling fifty-two conductive pads on the flex-circuit member isdesigned for operative engagement with cartridge pads on a 600 dpi blackinjet cartridge 64 (see FIG. 9).

The preferred structure and techniques for preventing mistakeninstallation of a 600 dpi black printhead in a color printhead chute, oralternatively the mistaken installation of a 300 dpi color printhead ina black printhead chute is described in the copending applicationsidentified above and incorporated by reference herein.

Because of the differently configured electrical interconnect on the 600dpi cartridge, and in order to avoid substantially changing the existingX/Y/Z datum configuration of the carriage, a unique interconnect schemeis employed. In that regard, the X-axis cartridge datums 65 engage theX-axis carriage datums 66, and the Y-axis cartridge datums 67 engage theY-axis carriage datums 68, and the Z-axis cartridge datums 69 engage theZ-axis carriage datums 70 in a manner more fully described in thecopending applications identified above and incorporated by referenceherein.

As best shown in FIGS. 9-11, a previously existing spring assemblyincluding a backing sheet 74, a plate 76 and a gimbal spring 78 aresized for fitting into apertures 80 of flex-circuit frame 82 to assureproper electrical interconnection for the three color cartridges. Suchresilient structure is described more fully in copending applicationsidentified above and incorporated herein by reference.

A unique spring assembly for the 600 dpi cartridge interconnect includesan unitary resilient foam member 84 which fits in a seat 86 which islarger than the aperture 80. A mounting peg 88 fits into matching hole90 which along with bottom and lower ledges 91, 93 and upper side andtop ledges 92, 94 hold the foam member in proper position to assureoperative engagement across the electrical interconnect. The structureand function of the flex-circuit frame, which has been modified toincorporate the unique features of the present invention, is describedmore fully in copending applications identified above and incorporatedherein by reference.

FIGS. 7-8 show the preferred mounting relationship between a 300 dpinozzle array 96 of the color printheads and a 600 dpi nozzle array 98 ofthe black printhead. Control circuitry 99 on the substrate enables thethree hundred firing resistors of the black printhead to be controlledthrough fifty-two electrical interconnect pads, and similarly enablesall one hundred four firing resistors of each color printhead to becontrolled through thirty-two electrical interconnect pads. Themultiplexing circuit scheme for such control circuitry is described morefully in copending applications identified above and incorporated hereinby reference.

FIG. 12 schematically shows the difference between the 300 dpi printoutproduced by the color pens (i.e., pen cartridges) and the 600 dpiprintout of the black pen of the preferred embodiment described herein.Of course, it would be possible to incorporated different combinationsof resolution in different printheads wherein the resolution differencemay be arbitrary, depending on the printheads available and alreadydeveloped, or wherein the resolution difference may be decimally related(e.g., 20% greater resolution, 30% greater resolution, etc.) orfractionally related (300 dpi with 400 dpi; 300 dpi with 450 dpi, etc.).In that regard, the invention can be implemented with any of theexisting inkjet cartridges which are currently available, with the bestresults occurring with printheads in the range of 180 dpi or greater.

It will therefore be appreciated by those skilled in the art that theinvention as shown and described herein allows different types ofinterconnects and different types of print cartridges such as cartridgesof different print resolutions to be used in one product.

This invention allows higher resolution and speed to occur forfrequently printed features such as text and the most frequent colorcomponents of graphics such as black. Thus by printing these frequentfeatures and components faster and at a higher resolution, the entirepage is faster and of higher quality and is more comparable with laserprinting performance (8+ pages per minute) and laser printing quality(600 dpi resolution).

The new form of resilient interconnect member disclosed herein allowsfor optimization and customization for the particular contact pattern ofdifferent cartridges in the same carriage. Thus, the size of thecarriage and the way that the cartridge is held in the carriage has tochange very little between subsequent generations of printers. In otherwords, the required design change to the printer is minimized, thecarriage does not have to grow wider nor taller, and the printer doesnot have to grow wider nor taller.

While specific illustrated embodiments have been shown and described, itwill be appreciated by those skilled in the art that variousmodifications, changes and additions can be made to the methods,structures and apparatus of the invention without departing from thespirit and scope of the invention as set forth in the following claims.

We claim as our invention:
 1. A printer/plotter with a carriage forremovably mounting at a same time a plurality of printheads,comprising:a frame for holding media in a print zone; a carriage movablysupported on said frame for traversal over said print zone along ahorizontal carriage axis; a first printhead having first electricalinterconnect means for receiving a first set of print activationsignals; a second printhead having a second electrical interconnectmeans for receiving a second set of print activation signals; means formounting said first and second printheads on said carriage in anadjacent first carriage chute and a second carriage chute along saidcarriage axis, for printing by said first printhead and said secondprinthead of respective horizontal swaths on the media in said printzone, said mounting means further includinga first conductive assemblywithin said first chute for mechanically and electrically engaging saidfirst electrical interconnect means, said first conductive assemblyincludinga first array of conductive pads matching said first electricalinterconnect means and first resilient means extending from a firstrecess or aperture within said first chute and coextensive with saidfirst array for maintaining a pressurized interconnection with saidfirst electrical interconnect means when said first printhead is mountedin said first chute, and a second conductive assembly within said secondchute for mechanically and electrically engaging said second electricalinterconnect means through a second recess or aperture in said carriage,said second conductive assembly includinga second array of conductivepads matching said second electrical interconnect means and secondresilient means extending from a second recess or aperture within saidsecond chute and coextensive with said second array for maintaining apressurized interconnection with said second electrical interconnectmeans when said second printhead is mounted in said second chute,wherein said first printhead and said second printhead each have a sameexternal size and a same external datum configuration, said adjacentfirst carriage chute and second carriage chute each have a samepredetermined chute width along said carriage axis, said first arraycovers a larger area than said second array, and said first array has agreater number of columns of conductive pads along said carriage axisthan said second array.
 2. The printer/plotter of claim 1 wherein saidfirst printhead includes a black printhead and said second printheadincludes a color printhead.
 3. The printer/plotter of claim 2 whereinsaid color printhead generates a color component selected from a groupconsisting of cyan, magenta, yellow, red, green and blue.
 4. Theprinter/plotter of claim 2 wherein said black printhead has a higherresolution than said color printhead.
 5. The printer/plotter of claim 1wherein said first printhead has a wider printing swath in a directionnormal to said carriage axis than said second printhead.
 6. Theprinter/plotter of claim 1 wherein said first printhead has a higherresolution than said second printhead.
 7. The printer/plotter of claim 3wherein said second printhead includes three adjacent color printheadseach associated with a different said color component, and any twoadjacent ones of said color printheads and said black printhead have asame center-to-center spacing.
 8. The printer/plotter of claim 1 whereinsaid first array and said array are each defined on a respectiveflex-circuit member.
 9. The printer/plotter of claim 1 whereinsaid firstresilient means is different in construction and operation from saidsecond resilient means, said first resilient means includes foam meansfor actively engaging said first electrical interconnect means, and saidsecond resilient means includes metal spring means for operativelyengaging said second electrical interconnect means.
 10. Theprinter/plotter of claim 9 whereinsaid first recess or aperture is wideralong said carriage axis than said second recess or aperture, said firstarray covers a greater width along said carriage axis than said secondarray.